(1) Estimating avg or mean daily requirement (EAR) of a representative sample of a life-stage and gender group.

(2) Estimating variability in the requirement of the nutrient for the target population.

(3) Setting the RDA at 2 standard deviations above the avg requirement. This amt should be sufficient to satisfy the requirements of approximately 97.5% of the individuals in the life-stage and gender group.

If the standard deviation (SD) of the EAR is available, the RDA is set at two SDs above the EAR:

RDA = EAR + 2 SD EAR

If data about variability in requirements are insufficient to calculate a SD, a coefficient of variation (CVEAR) of 10% is assumed:

RDA for energy – Same as the estimated average requirement of a population group. May be used as a general guide for a population group but may be entirely inappropriate for a given individual since energy needs can vary greatly from person to person and are not easily predicated without detailed information about body size, body composition and physical activity.

RDA for nutrients – Set high enough so it meets the upper limit of variability.

Inadequate intake of essential nutrients

Þ depletion, disease

Excessive intake of essential nutrients

Þ toxicity, or deficiency of another nutrient by interfering with absorption/utilization.

Can water soluble vitamins be toxic?

Yes:

(1) can have (or metabolite) a direct toxic effect.

(2) Can lead to dependency states and withdrawal symptoms.

(3) Can mask symptoms of a concurrent disease.

(4) Can interact with other vitamins or drugs.

Ý B6 Þ ataxia, sensory nervous system dysfunctoin.

Can minerals be toxic?

Yes, but not all are listed in RDA due to insufficient data.

Nutrition Labeling and Education Act of 1990

– Require "Daily Values" on labels

population weighted average of the 1989 RDAs for adults and kids >4 y/o – % DV - percent of Daily Value

Unless FDA has direct evidence that a dietary of vitamin/mineral supplement is inherently dangerous or marked with an illegal claim, it will not and cannot regulate it. Therefore, Americans cannot rely on the federal government to protect them from supplement overuse or misuse or poor quality control.

Examples of Vitamin deficiency and overdose

(more details later):

Vitamin B6 (pyridoxine)

– B6 deficiency: weakness, difficulty walking, irritability, mental depression (could be due to the fact that B6 (in tranaminations) is a cofactor in the reactions: tryptophan

ÞÞ serotonin and glutamic acid ÞÞ GABA)

Vitamin A

– Vitamin A toxicity results in bone resorption. There are two forms of Vitamin A: